The present invention relates to tracking systems and, in particular, it concerns methods for displaying point-of-interest coordinate locations in perspective images and for coordinate-based information transfer between perspective images on different platforms.
By way of introduction, it is known to employ image processing to identify and/or designate points of interest (or regions) in a wide range of different applications. Examples include, but are not limited to, identification and treatment of diseased areas of crops, early identification and extinguishing of forest fires and image-processing-based navigation aids. In each of these cases, it is common for a point-of-interest (“P.O.I.”) to be identified in a first perspective view, for example from an aerial survey of crops or a specialized airborne fire detection system. It is then desirable to identify the same P.O.I. as viewed from another platform, or from the same platform relocated at a new viewpoint, for example, a crop-duster or fire-extinguishing aircraft. The present invention addresses the transfer of the P.O.I. information in a compact but precise format to the second (or displaced) platform.
The present invention relies upon techniques of image registration between images viewed at different viewing angles. These techniques per se are well known in the art and will not be dealt with here in detail.
Israeli Patent No. 111069 to Sroka et al., hereby incorporated by reference for all purposes as if fully set forth herein, describes a method and system for marking object images acquired at high zooming by an airborne imaging device on a reference image having a wide field of view of the scene. This document does not address the question of information transfer between different platforms.
When image-based tracking systems are used on multiple platforms, information transfer between the platforms is complicated by the different viewing directions of the separate platforms. Even when a point-of-interest, or point-of-interest-related information, is identified in the context of images acquired from a first platform, this information cannot readily be used to identify the point-of-interest or update the point-of-interest-related information in the context of images acquired from another platform.
U.S. Patent Application Publication No. 2002/0196248 to Kraus et al., hereby incorporated by reference for all purposes as if fully set forth herein, partially addresses this problem. Specifically, it describes a method for sharing visual information between a number of command and control (“C&C”) units. Although point-of-interest designation is performed in the context of a perspective image, presentation of the information to other users is done in the context of a reference map. This renders it very difficult for the user to integrate the available information with the real-time image interface.
In the context of head-up displays (“HUDs”) and helmet-mounted displays (“HMDs”), it is known to present various symbols and other information spatially superimposed over corresponding objects in a scene viewed directly by a pilot. In some cases, position information for the symbols may be derived on the basis of the aircraft position as indicated by an inertial navigation system (“INS”) and/or global position system (“GPS”). The resolution of such systems is in the order of degrees, and is hugely inferior to the resolution which can be achieved by image correlation in high-resolution optical imaging systems.
There is therefore a need for methods for displaying point-of-interest coordinate locations in perspective images and for coordinate-based information transfer between perspective images on different platforms.